No matter what display mode you're in, I don't think any of them make it so that not even the AF points or 3x3 grid (if you have it turned on) show up in the EVF. And that is what this is.
When I say nothing in the EVF, again, I mean NOTHING. Even though I have the 3x3 grid turned on, it's not there. No AF points show up at all. All you see is the feed of what the sensor is seeing, nothing else. When I turn the camera off and then back on, everything comes back, including the 3x3 grid, the AF points, and all of the other info.
This is not just me accidentally putting the camera into a certain mode without realizing it. This is a bug.